1. Field of the Invention
This invention generally relates to a bicycle derailleur. More specifically, the present invention relates to a bicycle derailleur having a linkage arrangement operatively disposed between a base member and a movable member that regulates an actuation ratio for shifting the movable member.
2. Background Information
Generally, a front derailleur is mounted to the bicycle frame adjacent to the front chain rings to shift a chain laterally between the front chain rings. A front derailleur includes a fixed or base member that is non-movably secured to the bicycle frame. A front derailleur further includes a movable member or chain guide that is movably supported relative to the fixed member such that the movable member moves between at least two lateral shift positions to shift the chain between the front chain rings. Typically, a linkage assembly is coupled between the fixed member and the movable member in order to movably support the movable member. The movable member typically has a pair of cage plates or guide plates arranged to selectively contact and move the chain between the front chain rings. Every derailleur has an “actuation ratio” or “shift ratio” which refers to the ratio between a movement amount of an actuation element, e.g. a cable or a shaft of a motor and a transverse travel amount of the movable member.